1. Field of the Invention
This invention relates to a method for handling such alkylaminoalkyl (meth)acrylates as dimethylaminoethyl acrylate, diethylaminoethyl acrylate, and dimethylaminoethyl methacrylate as during storage, transport, transfer, haulage etc. and a method for preventing them from coloration.
2. Description of Related Art
Alkylaminoalkyl (meth)acrylates are useful as a dye-affinity improver for fibers, an antistatic agent for plastics, a pigment dispersant for coating materials, an ultraviolet-curing auxiliary etc. and are used in the form of varying kinds of derivatives as produced by quaternization of amino groups. In addition thereto, the derivatives producing by homopolymerization thereof or copolymerization thereof with an unsaturated compound are used as a fiber treating agent, a toner binder, a coating material, a lubricant additive, an adhesive agent, an ion-exchange resin, a cationic macromolecular flocculant etc. and are finding utility in a wide range of applications.
Since such an alkylaminoalkyl (meth)acrylate contains a double bond, an ester moiety, and an amino group in the molecular unit thereof, it abounds exceptionally in reactivity and, at the same time, suffers excessive unsteadiness. When this compound is put to storage, therefore, it at once yields to coloration and gives rise to a polymer and this trend gains in severity with time. When the discolored alkylaminoalkyl (meth)acrylate is used in manufacture, the secondary product consequently obtained is also discolored. The desirability of preventing this compound from this coloration and enabling it to acquire stability, therefore, has been finding unusually enthusiastic recognition.
A example cited in JP-A-04-169,559, for example, disclosed the effect that the coloration of an alkylaminoalkyl (meth)acrylate does not advance so much when it is stored in a glass container as when it is stored in a container made of stainless steel (SUS 304). The storage in glass containers, however, boosts the cost of equipment on a commercial scale. The glass containers are at a disadvantage in being deficient in strength and difficulty to manufacture in large sizes as compared with metallic containers, heavy, and inconvenient to handle. Though containers whose interior are coated with chemically inactive fluorine resin are usable for storing the compound under discussion, they are deficient in service durability.
Concerning the storage of an alkylaminoalkyl (meth)acrylate, JP-A-04-134,054 and JP-A-04-169,559 disclosed the effect that the coloration of an alkylaminoalkyl (meth)acrylate is allayed when the compound is stored in an atmosphere having no oxygen content or an atmosphere having only a low oxygen content. The methods of storage disclosed by these patent publications, however, incur a high cost of electric power because they require to use electric power for lowering the concentration of oxygen or the temperature of conservation. This storage is practicable in a stationary storage container. When it is applied to such transportable containers as shipping containers and tank lorries, however, it has the problem of operational inefficiency because these containers assume an atmosphere of air whenever they are packed with a load and they consequently require to lower the oxygen concentration of the load.
The patent publications also disclosed the effect that the coloration of the alkylaminoalkyl (meth)acrylate does not proceed when the compound is stored at a low temperature of not higher than 5xc2x0 C. From the viewpoint of securing stability, however, the alkylaminoalkyl (meth)acrylate is preferably transported at a low temperature of not higher than 5xc2x0 C. The use of the low temperature, however, is at a disadvantage in adding to the cost of transportation. Moreover, in terms of handling, even the normal temperature proves advantageous for the transportation so long as it enables the compound to secure stability enough to prevent coloration and polymerization.
JP-A-04-134,053 mentioned above discloses a method which has recourse to the addition of hydroquinone monomethyl ether in combination with the presence of oxygen. Even when the alkylaminoalkyl (meth)acrylate is stored in the conditions proposed thereby, it possibly generates a while precipitate, stains the container used for storage or transportation, and blocks pipings for a cause yet unknown.
The addition of a stabilizer for the purpose of preventing polymerization has been studied in connection with the method for storage of alkylaminoalkyl (meth)acrylate. JP-A-53-144,521, for example, discloses a method for preventing N,N-dimethylaminoethyl acrylate from polymerization and coloration during storage by the use of phenothiazine. The addition of such a polymerization inhibitor, however, brings no decrease in the white precipitate. JP-A-10-182,569 discloses a method which, for the purpose of stabilizing in color, comprises in handling the compound with a phenolic compound in the presence of at least one member selected from the group consisting of amid group-containing compounds, phosphorous esters, phosphoric esters, and phosphines. The use of the new additive results in boosting the cost of storage.
This invention is aimed at preventing an alkylaminoalkyl (meth) acrylate in storage from succumbing to coloration, giving birth to a precipitate, and yielding to polymerization.
Specifically, this invention concerns a method for handling an alkylaminoalkyl (meth)acrylate represented by the general formula (1) 
(wherein R1 represents a hydrogen atom or a methyl group, R2 an alkylene group of 1-4 carbon atoms, R3 a hydrogen atom or an alkyl group of 1-8 carbon atoms, and R4 an alkyl group of 1-8 carbon atoms) by keeping in contact with stainless steel, wherein said stainless steel contacting with said compound is not more than 1.6 xcexcm for the Ra defined in JIS (Japanese Industrial Standard) B 0601.
Further, this invention concerns a method for handling an alkylaminoalkyl (meth)acrylate represented by the general formula (1) 
(wherein R1 represents a hydrogen atom or a methyl group, R2 an alkylene group of 1-4 carbon atoms, R3 a hydrogen atom or an alkyl group of 1-8 carbon atoms, and R4 an alkyl group of 1-8 carbon atoms), wherein the water concentration is not more than 0.1% based on the volume of gas phase part contacting with said compound and concentration of (meth)acrylic acid is not more than 0.1% based on the weight of said allkylaminoalkyl (meth)acrylate.
This invention also concerns a method for preventing alkylaminoalkyl (meth)acrylate represented by the general formula (1) 
(wherein R1 represents a hydrogen atom or a methyl group, R2 an alkylene group of 1-4 carbon atoms, R3 a hydrogen atom or an alkyl group of 1-8 carbon atoms, and R4 an alkyl group of 1-8 carbon atoms) from coloration by keeping in contact with stainless steel, wherein said stainless steel contacting with said compound is not more than 1.6 xcexcm for the Ra defined in JIS (Japanese Industrial Standard) B 0601.
Besides, this invention concerns a method for preventing alkylaminoalkyl (meth)acrylate represented by the general formula (1) 
(wherein R1 represents a hydrogen atom or a methyl group, R2 an alkylene group of 1-4 carbon atoms, R3 a hydrogen atom or an alkyl group of 1-8 carbon atoms, and R4 an alkyl group of 1-8 carbon atoms) from coloration, wherein the water concentration is not more than 0.1% based on the volume of gas phase part contacting with said compound and concentration of (meth)acrylic acid is not more than 0.1% based on the weight of said alkylaminoalkyl (meth)acrylate.
Further, this invention is directed at providing an apparatus to use for the method according to Item 1, which comprises a container made of stainless steel whose wall surface contacting with said compound is not more than 1.6 xcexcm for the Ra defined in JIS B 0601 and means for retaining the water content in the gas phase part of a storage container below 0.1 vol. %.